The acute effects of ethanol are mediated by binding to specific sites on proteins. We propose to elucidate the actions of ethanol on the GABAa and glycine receptors, two critical molecular targets for ethanol, by combining molecular, electrophysiological and behavioral methods. Aim 1 will elucidate the specific location and orientation of the amino acids that form the ethanol binding site in heteromeric GABAa receptors. Our ongoing studies of glycine receptors suggest that zinc, a physiological modulator of glycine receptors, is important for ethanol action on these receptors, and Aim 1 will also define the molecular basis of this interaction. In Aim 2, we will use GABAa and glycine receptor knockout and knockin mice to specify the behavioral effects of ethanol that are due to actions on these receptors. Aim 3 will evaluate the neuronal consequences of receptor mutation. This will be accomplished by genomic analysis of key brain regions and by electrophysiological study of the mesolimbic reward pathway. Aim 3 will also define effects of chronic ethanol consumption on global gene expression changes in the ventral tegmental area and nucleus accumbens, the two key areas of the mesolimbic pathway. These studies will use wild type mice and mice with GABAa or glycine receptors that are engineered to be insensitive to ethanol action. This novel approach will allow us to link changes in gene expression (and behavior, Aim 2) to alcohol actions on specific receptors. The long-range goal of this work is to define key protein sites that can serve as targets for new therapies to alleviate alcohol reinforcement, dependence an relapse.